THE BLOOJ). 179 



animals, and is, up to the present, the most powerful haemolytic 

 agent known. 



As to vitality, it is known that the corpuscles of the blood that 

 have escaped from the circulatory system, as well as those from 

 defibrinated blood, when reintroduced into the living blood-stream, 

 retain their vitality. 



THE WHITE CORPUSCLES. 



The white corpuscles are colorless, spherical little bodies which 

 are a little larger than the red ones and much less numerous. Each 

 is about %soo i ncn i n diameter and is composed of granular proto- 

 plasm that is highly refractile and without any enveloping mem- 

 brane. 



In striking contrast to the erythrocytes, the leucocytes possess 

 not only one, but usually three nuclei; even four are not uncom- 

 mon. Within the nuclei may be defined several distinct nucleoli. 



When examining a section of blood, it is at once a striking fea- 

 ture how few are the white as compared with the red corpuscles. In 

 the average field but three or four are found, while at the same 

 time hundreds of erythrocytes are noticed. The average is but 1 

 white for every 500 or 600 red ones. 



This proportion does not pretend to convey an accurate idea of 

 their relationship because of the frequent fluctuations of the white 

 corpuscles even in a single day. They increase during digestion and 

 diminish during abstinence. Seven thousand five hundred white 

 corpuscles are found in a cubic millimeter of blood. 



Bleeding, lactation, quinine, local suppuration, pregnancy, and 

 leucocy tha3rnia increase the white corpuscles ; their number is dimin- 

 ished by large doses of mercury. 



The proportionate number of leucocytes that is found in blood 

 drawn from its containing vessels is no criterion of the number 

 found within the blood-stream. As soon as blood is drawn from the 

 body, for no accountable reason, an immense number of white cor- 

 puscles disappears. It is stated that there remain but one-tenth of 

 the number previously found in circulation. 



Colorless corpuscles are not essentially peculiar to the blood- 

 stream nor to be found only in it, for similar corpuscles are found 

 in lymph, chyle, adenoid tissue, the marrow of the long bones, and 

 Iso as wandering cells in connective tissue, drawn thither by inflam- 

 ition and by bacteria. 



Varieties. According to Ehrlich, they may be 'separated into 



